1. Field of the Invention
This invention pertains generally to electric motors and generators for use in appliances. More specifically, this invention pertains stators wherein the bosses that secure the stator to an appliance component are formed entirely by a single monolithic insulating member. This eases manufacturing tolerance requirements.
2. General Background
Many appliances, such as laundry machines, utilize electric motors. In some cases, direct drive motors are utilized. In a direct drive system, the stator and the rotor of the motor are mounted directly to separate components of the appliance, rather than being connected directly to each other in a motor housing. Thus, the appliance components are rotationally mounted directly to each other and this indirectly rotationally mounts the stator and the rotor to each other.
Typically, the stator forms a ring and comprises several primary components. These components include a ring-shaped ferromagnetic core having a plurality of radially extending teeth, windings that encircle the teeth, and insulating members that electrically separate the windings from the core. The insulating members are often two monolithic injection molded plastic parts that are often referred to as end caps. Each of such insulating members is formed generally as a ring having teeth corresponding to the teeth of the core and is configured to wrap halfway around each tooth of the core. Thus, when the core is sandwiched between the two insulating members, each tooth of the core is encircled by the insulating material. The windings are then formed around the insulating material that surrounds each tooth.
In practice, it is known to form bosses on the insulating members for the purpose of creating a means for attaching the stator to an appliance component. Typically, each of the insulating members comprises a plurality of protrusion that line up with the protrusion of the other insulating member. Each aligned pair of protrusions forms a boss and each boss comprises a through-hole. The bosses thereby serve as a means for securing the stator to an appliance component via bolts. To prevent damage to the stator from over torquing the bolts, metal sleeves are typically inserted into the through-holes to provide a positive stop for the bolts. As can be appreciated, the length of such sleeves must be configured such that the insulating members are not over clamped but are at least sufficiently clamped to inhibit relative movement when they are bolted to an appliance component. However, because the two insulating members collectively form each boss, tight tolerances are required to prevent the compounded total tolerances from become too large. Thus, in practice, the dimensions of the insulating members are closely controlled, which adds to the costs of producing the stators.